If Phosphates are presentThere are swimming pool chemical treatments called Phosphate Removers that will reduce Phosphates. This will require several doses to bring the level down to 0 ppb (parts per billion)

(Fertilizer) NitrogensThe worst sort of chemical to get into swimming pools. There does not exist any chemical remover, a complete pool draining and refill with clean water is required.

Unfortunately, a pool drain will put you back into the hard water problem if you re-use the ground water, but for the sake of achieving water clarity, it is the lesser of the three evils to choose from in this scenario.

Opened my pool two weeks ago. The zeobrite was put in July 2011. I live in Minnesota so the pool is only running May-Oct. I had algae problems and had to backwash frequently. After about two hours the pressure kept building in the filter. So I followed Zeobrites instruction about treating the media with a salt solution. No change. Then I tried letting it soak with filter cleaner for 48 hours. Still no change. Then I opened the filter one last time to replace the Zeobrite with sand. The zeobrite was rock hard in many places. I also put Zeo in the filter in 2009. My pool is nearly clear now after three days of using regular sand. I will never used Zeobrite again.